1. Field of the Invention
This invention relates to a pumpable/injectable ceramic, and more particularly this invention relates to a ceramic composition that maintains low viscosity for extended periods of time to allow the composition to be pumped or injected into hard to reach geologic or manmade locations.
2. Background of the Invention
Disposal of hazardous waste, low-level radioactive waste or benign waste continues to present problems. Landfill space is becoming more scarce so that only nonrecyclable material or nonbiodegradable material is often considered the only candidates for land filling.
When hazardous material is land filled, care must be taken to prevent destabilization of the material, so that leaching will not occur.
Aside from land filling, efforts have been made to combine to-be-disposed-of-material with cement so as to form solid monoliths or waste forms for burial or for use as structural products. For example, U.S. Pat. No. 4,432,666 to Frey et al., discloses using cement and other water repellant binders to dispose of waste thought to be damaging to the environment. However, cement is unstable in many situations, for example when attempts are made to encapsulate halogenated materials.
U.S. Pat. No. 3,093,593 to Arrance discloses a method for vitrifying silicate materials to encapsulate radioactive waste. However, temperatures of up to 1,400.degree. C. are required to produce final waste forms.
In U.S. Pat. No. 5,645,518, awarded to the instant Assignee, a method to stabilize low-level mixed wastes, such as radioactive medical wastes and other such materials, is provided, wherein phosphate ceramics physically and chemically stabilize the waste at ambient temperatures. However, in such endeavors, final waste forms rapidly set. This rapid-setting feature causes various degrees of unworkability to the process, particularly in situations where low viscosity and long operational times are required. Such situations include where the material is to be blown, poured or injected into deep wells or crevices, in-situ stabilization of buried wastes, remediation at nuclear-accident and waste spillage sites, and pumpable refractory applications.
In addition to the drawbacks of the above-mentioned processes, commercially supplied materials for use as components (particularly the oxides) of the above processes are in forms adverse to formulating flowable mixtures. As a result, exothermic reactions become uncontrollable, leading to thicker slurries, with the final product lacking homogeneity. Also, the resulting rapid setting time of the ceramic does not provide adequate working time.
A need exists in the art for a formulation and a waste encapsulation process to accommodate stabilization of a myriad of waste materials in a myriad of deposition scenarios. The formulation and process should provide waste liquors having protracted, workable consistencies or viscosities to accommodate currently available pump- injection-, or spray application-equipment. The process should also provide a protocol for selecting and preparing components of the formulation so as to tailor the formulation for situations requiring varying degrees of viscosity.